1. Field of the Invention
This invention relates to earphones and methods of making the same to obtain earphones and earphone assemblies which reproduce sounds with very high fidelity and with minimum noise and which are suitable for use by the most discriminating listeners. The earphones and assemblies of the invention are very compact and light in weight, are highly reliable and are readily and economically manufacturable.
2. Background of the Prior Art
xe2x80x9cAudiophilexe2x80x9d earphones have been marketed for use by audiophiles or discriminating listeners interested in the highest possible sound reproduction. Such audiophile earphones have been ostensibly capable of effecting high fidelity sound reproduction although it has been recognized by many users as well as the makers of such earphones that they have left much to be desired with respect to fidelity of reproduction. It has apparently been assumed by such users and makers that deficiencies in quality of sound reproduction are an unavoidable result of the use of earphones.
In a separate audiometry art, earphones have also been developed and marketed in limited quantities for use in specialized audiometry applications to measure the responses of a patient""s ear and having features for obtaining desired response characteristics, one disclosure being contained in the Killion U.S. Pat. No. 4,763,753, issued Aug. 16, 1988. Another separate art, the hearing aid art, also contains many disclosures related to the achievement of improved response characteristics, including a paper entitled xe2x80x9cSMOOTHING THE ITE RESPONSE: THE BF-1743 DAMPED COUPLING ASSEMBLYxe2x80x9d by Mead C. Killion and William J. Murphy, first published in April 1981 and revised June 1982, by Industrial Research Products, Inc. Elk Grove Village, Ill. Such disclosures in the audiometry and hearing aid art relate to devices of relatively expensive construction which are designed for specialized applications and marketed in limited quantities. The applicability of the audiometry and hearing aid arts to the making of earphones for use in high fidelity sound reproduction has apparently gone unrecognized.
This invention was evolved after learning of the deficiencies of earphones marketed for use by audiophiles and with the general object of providing earphones which have improved high fidelity response characteristics and which are readily and economically manufacturable.
Important aspects of the invention relate to the recognition and discovery of problems with prior art arrangements and their causes and to an analysis of what is necessary to overcome such problems and otherwise provide improved earphones. It was discovered that one serious problem with audiophile earphones has been related to the failure to recognize the need to compensate for loss of external-ear resonance when using an earphone and the failure to provide compensating acoustic characteristics between the ear canal of a user and the transducer or receiver used to develop an audio signal from an applied electrical signal. It was further discovered that features of a damped coupling assembly of the hearing aid disclosed in the aforementioned Killion and Murphy paper might be applied with advantage to the construction of an audiophile earphone. With a damped coupling assembly as disclosed in that paper, a damper is coupled through a tube to an output port of a receiver and is disposed within the tip of an earmold. The arrangement produces a frequency response which will compensate for the loss of external ear resonance and which is largely independent of the total length of the coupling between the receiver and the earmold tip.
In accordance with the invention, an audiophile insert earphone is provided which uses a damped coupling assembly similar to that disclosed in the above-mentioned Killion and Murphy paper and operative to provide compensation for the loss of external-ear resonance. In accordance with one important feature of the invention, a pair of such earphones are combined in a dual earphone assembly usable for stereophonic reproduction.
Additional important features of the invention relate to features of construction which facilitate manufacture of insert earphones and which at the same time achieve reproduction of sounds with very high fidelity and with a high degree of reliability. Certain of such features relate to the provision of a housing member which can be readily molded from plastic in one piece and which serves the functions of connecting to an outlet port of a receiver, supporting a damper and providing a sound passage. The housing member also serves to releasably connect to a coupling device such as an earmold or ear tip and it performs all of such functions with a high degree of accuracy and reliability. Others such features relate to the provision of a resilient support for the receiver to minimize the effects of vibrations and noise and to methods of making the earphone to facilitate manufacture at low cost.
Another feature relates to the combination of electrical filters with the earphone and its damped coupling assembly to achieve optimum overall results.
Still another feature relates to a construction to facilitate removal and replacement of a damper and to the provision of a tool for that purpose.
This invention contemplates other objects, features and advantages which will become more fully apparent from the following detailed description taken in conjunction with the accompanying drawings.